Slipped Capital Femoral Epiphysis (SCFE) is a common adolescent hip disorder where the capital femoral epiphysis may be displaced posteroinferior relative to the metaphysis. SCFE may occur along the physis (also referred to as the growth plate) of the femoral head near a patient's hip joint. An exemplary instance of SCFE is illustrated in FIG. 1. Patients having SCFE may exhibit symptoms such as limping, inability to bear weight on the affected extremity, or hip, knee, or thigh pain. Patients with sudden and severe hip pain who cannot bear weight on the affected extremity, even with crutches, are classified as having unstable SCFE. In some cases, patients with SCFE may develop osteonecrosis of the femoral head after surgical treatment to repair or mitigate the effects of SCFE. The overall incidence of osteonecrosis associated with unstable SCFE is unknown, with estimates ranging from 10%-60% in literature. Due to the potentially high association between SCFE and osteonecrosis, many authors considering the issue have advocated for early treatment of unstable SCFE (typically within 24 hours of the onset of symptoms).
Particularly for unstable instances of SCFE, treatment often requires surgical intervention and insertion of one or more cannulated screws into the femoral head, through the physis, and into to femoral epiphysis in order to stabilize the osseous tissue and prevent further slippage of the tissue relative to the metaphysis. As is understood by those skilled in the art, cannulated screws have a hollow shaft forming a central passageway running longitudinally along the length of the screw. In certain instances, the screw may include one or more thread patterns along at least a portion of the exterior surface of the screw, and may include a screw head being formed by a portion of the screw, measured longitudinally, located at the end of the screw opposite the threaded end. As will be understood, the screw head may have an outer diameter larger than the diameter of the remainder of the cannulated screw. Currently, cannulated screws are often utilized in the treatment of SCFE by stabilizing the slipping epiphysis, and to stabilize bone fractures in joints, among other treatments.
Many considering the issue have hypothesized that increased intracapsular pressure and/or kinking of lateral epiphyseal vessels may lead to the disruption of the femoral head blood supply in unstable instances of SCFE. In certain instances, treatment of SCFE may include a capsulotomy procedure to relieve pressure in the femoral head and therefore decrease the likelihood of osteonecrosis in the joint. Therefore, methods and devices for intra-operatively monitoring the femoral head blood supply (epiphyseal perfusion) and epiphyseal pressure in patients with SCFE are needed to better understand the relationships between intracapsular pressure, epiphyseal perfusion, and the occurrence of osteonecrosis.